Perhaps one of the most challenging creative tasks for a writer would be to build an entire world from their potent imagination, something that’s done most often by authors of fantasy.

The most successful fantasy series of all time remains JRR Tolkien’s “Lord of the Rings” from the late 1930s. Since then, there have been other fantasy authors who have vied for “LOTR”-level acceptance.

The series of books that comes closest to Tolkien’s masterpiece would have to be George R.R. Martin’s “A Song of Ice and Fire,” a series that has sold millions of copies and been translated into various languages around the world.

There had been four books thus far: “A Game of Thrones” (1996); “A Clash of Kings” (1998); “A Storm of Swords” (2000); and “A Feast of Crows” (2005).

The series has been blessed with massive attention after HBO adapted the first book into a critically acclaimed mini-series. HBO is now working on the second volume.

Amid all this newfound glory and after a six-year delay, Martin’s “A Dance with Dragons” (Bantam Books, New York, 2011, 1040 pages) has swooped into bookstores with expectations as big as the book’s 1,040 pages, the most in the series.

Sex and death

What makes Martin’s Seven Kingdoms very different from Tolkien’s Middle Earth is its gritty edginess and relative realism. Yes, there are dragons and magic in the series, but the books focus mostly on its phalanx of flawed characters and their conspiracies little and big.

Martin matches the sword-fighting adventures with vivid sex and graphic death. It makes the books of “A Song of Ice and Fire,” in the vocabulary of the new century, “not safe for work.”

It does make for dense, enthralling reading. As Martin explains at the start of the book, “Dragons” is not exactly a sequel to “Crows.” Instead, a large part of the book occurs simultaneously with the last parts of “Crows,” though “Dragons” eventually emerges into sequel territory toward the end.

“Dragons” keeps its eyes on a lot of Martin’s characters. On the Wall, Jon Snow prepares for an enemy spoken only in terrified whispers even as he navigates the intentions of the people around him.

In Meereen, Daenerys Targaryen discovers the perils of being queen, the difficulties that come with keeping the only living dragons, as well as the burden that comes with choosing the right husband.

The dwarf Tyrion Lannister finds himself pursued, tormented and far from home. Armies are on the march and ships take to sea. The war between King’s Landing and the forces of Stannis Baratheon enter a new, fearful stage, while others are just trying to stay ahead and alive. In the process, as is Martin’s way, many others are killed in horrible ways.

Most jarring cliffhanger

While very well-written, “Dragons” would be impenetrable for new readers while followers of the series should be warned that an entire shipload of characters does not appear in “Dragons” at all.

“Who else is there to kill… Where does it end,” someone asks.

“It ends in blood, as it began,” someone else answers.

This is what lies at the scarred heart of “A Song of Ice and Fire: Vengeance,” not mythical creatures or spellcasting. What really pushes these lords and queens to do what they do is to get even—no matter how far they have to go.

In “Dragons,” Martin advances his overall plot forward and also ends with his most jarring and ambitious cliffhanger so far.

There are now only two chapters left in “A Song of Fire and Ice”— The Winds of Winter” and “A Dream of Spring”—though there’s no way of telling exactly when they will find flight to bookstores.

In “A Dance with Dragons,” Martin has written yet another excellent chapter in the history of Westeros and beyond, the most vividly visited fantasy realm since Middle Earth.

Available in hardcover from National Book Store.